Some Mesotron Observations by Simultaneous Registration at Two Stations

Abstract

Two cosmic-ray telescopes were used in these investigations, each being screened against the softer vertical component by 20 cm of lead. One telescope, permanently located at the lower station 142 feet above sea level, served as a "control" with reference to which readings of the second telescope were corrected for fluctuations caused by variations in atmospheric temperature, barometric pressure, and magnetic effects. The second telescope, after having recorded intensities at the lower station, was moved to a platform atop the Empire State Building, 1125 feet above sea level. Intensities here were measured both with and without a compensating layer of lead equivalent to the 35-millibar pressure difference between stations. Estimated mean life range of the mesotron was 9.7\ifmmode\pm\else\textpm\fi{}3 km, accuracy being limited chiefly by the comparatively short differential in height between stations. In the second part of this paper a series of correlations of ground values of mesotron intensities with the height variations of the 1000-, 850-, 700-, 500-, 300-, 200-, and 100-millibar pressure levels of the atmosphere is described. From these observations the existence of two production levels for mesotrons is inferred from the position of two peaks in the value of the correlation coefficients, peak values being found for the 500- and 100-mb observations. Mesotron decay coefficients for these two levels were approximately the same and equal to -0.0705 ${\mathrm{km}}^{\ensuremath{-}1}$, thus giving a mean life range of 14.2\ifmmode\pm\else\textpm\fi{}1.4 km consistent with an effective mesotron spectrum of 2.37\ifmmode\times\else\texttimes\fi{}${10}^{9}$ ev assuming the rest lifetime of the mesotron as 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ sec.